Effects of clear-cutting on decomposition processes in leaf litter and the nitrogen and lignin dynamics in a temperate secondary forest

The effects of clear-cutting on the decomposition rate of leaf litter and on nitrogen (N) and lignin dynamics were investigated in a temperate secondary forest. Decomposition processes were examined over an 18-month period by the litterbag method and compared between a clear-cut site and an adjacent uncut control site using leaf litter from five dominant tree species (Clethra barvinervis, Quercus serrata, Camellia japonica, Ilex pedunculosa and Pinus densiflora). The decomposition rate for litter from C. barvinervis, Q. serrata and I. pedunculosa was significantly greater in the clear-cut plot than in the control plot, and there was no significant difference between plots for C. japonica and P. densiflora. Water content of litter was consistently lower in the clear-cut plot than in the control plot. Nitrogen mass increased after 6 months in the control plot, whereas no net increase of N was observed in the clear-cut plot. Nitrogen concentration increased with respect to accumulated mass loss of litter and was consistently lower in the clear-cut plot for all five species. The mass of lignin remaining in decomposing litter was generally lower in the clear-cut plot, but lignin concentration in decomposing litter was not significantly different between the clear-cut and control plots.     

Effects of the second-generation larch plantations onsoil fertility and tree growth

Larch is one of the most important plantation species in the northeast region of China. After clear cutting of larch plantations it is the urgent problem to besolved that whether the second generation is continuously plant6d, whether the soil fertility is decreasing and the plantstion is how to be managed onthe forestry produCtion. In odder tO realize the secondgenerahon Of larch plantstions and to provide thetheoretical base and the reasonable managementmeasures, we inventoried the groWth o…     

Effects of decomposed leaf litter mixtures from Platycladus orientalis and broadleaf tree species on soil properties

Determining the effects of decomposed leaf litter mixtures, consisting of litter from different tree species, on the properties of soil is important for evaluating nutrient cycling and interspecific relationships. In this study, leaf litter mixtures consisting of Platycladus orientalis (L.) Franco combined individually with eight broadleaf plant species were ground and mixed with soil to analyze the effects of their decomposition on the quantity of soil microbes, the activities of soil enzymes, and the soil chemical properties and to determine the interactions between the different types of litter within a mixture during decomposition. In terms of soil properties as a whole, we found that when P. orientalis litter was mixed separately with litter from Amorpha fruticosa L., Caragana microphylla Lam., Betula platyphylla Suk., or Hippophae rhamnoides L., the resulting litter mixtures showed synergistic interaction effects on soil, but when P. orientalis litter was mixed with litter from Populus simonii Carr., Ulmus pumila L., Robinia pseudoacacia L., or Quercus liaotungensis Koidz. showed antagonistic interaction effects.     

Growth characteristics of multipurpose tree species,crop productivity and soil properties in agroforestry systems under subtropical humid climate in India

Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m （2500 stems·hm^-2） could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m^3·hm^-2 with mean annual increment （MAI） of 2.54×10^-2 m^3.treel.a^-1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m （1111 stems.hm^2） produced appreciably high timber volume of 315 m^3.hm^-2 and 165 m^3.hm^-2 with MAI of 1.77×10^-2 m^3.tree^-1·a^-1 and 0.92×10.2 m^3.tree^-1.a^-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m^3.hm^-2 with MAI of 1.47×10^-2 m^3.tree^-1.a^-1 followed by Samania saman （140 m^3.hm^-2）, Albizziaprocera （113 m^3·hm^-2） and Tectona grandis （79 m3.hm^-2） with MAI of 1.40, 1.13 and 0.78 × 10^-2 m^3 .tree^-1a^-1, respectively in 4 m × 4 m spacing （625 stems.hm^-2）. Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice （Oryza sativa - variety, AR-11）, groundnut （Arachis hypogaea - variety, JL-24） and sesamum （Sesamum indicum - variety, B-67） were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple （Ananas comosus - variety Queen）, turmeric （Curcuma longa -variety RCT -1） and cowpea （Vigna sinensis - variety Pusa Barsati） as forage crop were raised. The productivity of p     

冀北山地不同树种组成桦木林枯落物及土壤水文效应

为弄清不同树种组成的林分对林地枯落物及土壤持水能力的影响,采用浸泡法和双环法对冀北山地5种不同树种组成的桦木林进行研究,结果表明:1林地枯落物半分解层储量均大于未分解层,总储量变化范围为12.85~20.87t/hm~2,白桦纯林储量最大,阔叶混交林最小;2枯落物最大持水量变化范围为73.27~106.99t/hm~2,有效拦蓄量变化范围为59.22~81.86t/hm~2,均为杨桦混交林最大、落桦混交林最小;3枯落物持水量与浸泡时间呈对数关系,随时间推移逐渐增大,而吸水速率与浸泡时间呈指数关系,随浸泡时间推移而逐渐下降;4土壤容重是油松白桦林最大、杨桦混交林最小,总孔隙度是杨桦混交林最大(60.66%)、阔叶混交林次之(59.31%)、油松白桦林最小(45.43%),土壤最大持水量和有效持水量均是杨桦混交林最大、阔叶混交林次之、油松白桦林最小;5土壤入渗速率和入渗时间呈明显幂函数关系。综合来看,杨桦混交林和阔叶混交林枯落物和土壤持水能力较强。     

印地安潮湿亚热带的多种用途树种的生长特性以及农林系统中作物产量和土壤特性(英文)

在印地安具有亚热带潮湿气候特点的东北地区,本文对几种多种用途的树种进行研究。选择12种多用途树种种植在农林系统中,耳果相思(Acacia auriculiformis),种植间距为2m×2m(2500 个·hm-2),有很大的生长潜力。在 10 年期的短期轮伐中,每年有很高的产量(635 m3·hm-2),平均每年增涨量为 2.54×102 m3·tree-1·a-1,可以满足薪碳材的需要。所以,耳果相思(Acacia auriculiformis)是一种短期轮伐树种,适合种植在潮湿亚热带气候地区。另一方面,16年树龄的桉树(Eucalyptus hybrid)和黄兰(Michelia champaca) 种植间距为3m×3m (1111个·hm-2),分别有较高的生长量(315 m3·hm-2和165 m3·hm-2),平均每年每棵树增长量分别为1.77×10-2 m3和0.92 × 10-2 m3。16年树龄的印度石梓(Gmelina arborea) 木材产量为147 m3·hm-2,每年每树的增长量是 1.47×10-2 m3。其次为 Samania saman(140 m3·hm-2)和柚木(Tectona grandis (79 m3·hm-2)),平均每年每树的增长量分别是 1.40,1.13和0.78×10-2 m3。毒鼠豆属植物(Gliricidia maculate) 和银合欢(Leucaena leucocephala) 可以用作农厂的围栏并提供农作物的肥料。在植物园,种植树木的最初 8 年间,可以种植高地水稻(Oryza sativa–variety, AR-11), 落地花生(Arachis hypogaea–variety, JL-24)和胡麻(Sesamum indicum–variety,B-67)。由于林下郁闭度太大,在耳果相思(Acacia auriculiformis)林下的农作物产量不高,与空旷地的农作物比较产量有所降低。树木种植 8 年后,种植草料作物如,凤梨、姜黄、豇豆,它们的产量在印楝(Azadirachta indica)林下很高。高产量的农作物和园艺植物与具有高产量多种用途树种一起种植构成了有发展前景的农林系统,并改变土壤特性,改善土壤酸度,提高土壤有机质,降低土壤腐蚀度,提高土壤含水量。     

Effect of removal of logging residue on nutrient leaching and nutrient pools in the soil after clearcutting in a Norway spruce stand

Following clearcutting applying the conventional stem-only harvesting method in a Norway spruce (Picea abies (L.) Karst.) stand and different levels of removal of logging residue, the nutrient fluxes from the heaps of logging residue and from the O horizon were monitored over four growing seasons and the soil nutrient pools were determined. Three levels of removal of logging residue were carried out using (i) conventional stem-only harvesting (no residues removed); (ii) residues removed; and (iii) removal of branches (foliage left on site). The heaps of logging residue were a minor source of inorganic N entering the soil in the water percolating through the heaps, but they were a significant source of organic N, P, Ca, Mg, and especially K. Nutrient fluxes from the O horizon were in general greater under the heaps of logging residue as compared to soils without overlying logging residue. The leaching of inorganic N from the O horizon under the heaps of logging residue resulted in a net loss of these compounds, while the O horizon without overlying logging residue gained N. The removal of logging residue significantly decreased the extractable K pools in the soil while it or conversely, the presence of residue heaps had no significant effect on the pools of organic matter and the pools of N, P, Ca, and Mg in the O horizon and in the 0–10 cm soil layer. The results show that the short-term effects of logging residue on nutrient dynamics in the soil can be complex and difficult to interpret in terms of site productivity as there are changes in the nutrient fluxes, which imply the opposite effects on site productivity. However, the results do indicate that, in the short-term, the removal of logging residue does not impair pools of N in the soil nor site productivity on sites where the availability of N limits productivity.     

Litter dynamics and soil properties under different tree species in a semi-arid region of Rajasthan,India

Litterfall and decomposition are the two main processes accounting for soil enrichment in agroforestry. The extent of enrichment in soil properties depends on the tree species, management practices and the quantity and quality of litter. A field investigation was carried out to study litterfall production, decay rates, release of nutrients and consequent changes in soil physicochemical properties under crowns of four multipurpose tree species (MPTs) in irrigated conditions in farm fields. The species were Prosopis cineraria (L.), Dalbergia sissoo (Roxb.) ex DC, Acacia nilotica (L.) Del. and Acacia leucophloea (Roxb.) Willd. Annual accretion of litter ranged from 36 to 54 kg tree⁻¹ year⁻¹ and was highest under D. sissoo and lowest under A. nilotica. Total litterfall production was in the order: P. cineraria > A. leucophloea > A. nilotica > D. sissoo. P. cineraria showed the highest NPK concentration in litter. For all MPTs, a large pulse of litterfall coincided with the winter season (November to February). Litter of P. cineraria decomposed fastest while that of A. nilotica was slowest. More than 95% of the leaf litter of P. cineraria decomposed in 6 months, of D. sissoo in 7 months and A. leucophloea and A. nilotica in 9 months. Decomposition rate of litter was highly correlated with neutral detergent fibre (NDF) (r = −0.94) and P (r = −0.91) concentration. N, P and K release were best correlated with NDF, acid detergent fibre (ADF), P, lignin, lignin/N and C/P ratios and NDF alone explained 88% to 94% of the variability in litter decomposition and nutrient release rates. There was significant build up of soil organic carbon and available NPK in the agrisilvicultural systems but also a decrease in soil pH. Build up in soil fertility was significantly correlated with litterfall and soil improvement was greatest under P. cineraria.     

Interacting effects of canopy gap, understory vegetation and leaf litter on tree seedling recruitment and composition in tropical secondary forests

We experimentally investigated interacting effects of canopy gaps, understory vegetation and leaf litter on recruitment and mortality of tree seedlings at the community level in a 20-year-old lowland forest in Costa Rica, and tested several predictions based on results of previous studies. We predicted that experimental canopy gaps would greatly enhance tree seedling recruitment, and that leaf litter removal would further enhance recruitment of small-seeded, shade-intolerant seedlings in gaps. We created a large (320–540 m²) gap in the center of 5 out of 10 40 m × 40 m experimental plots, and applied the following treatments bimonthly over a 14-month-period in a factorial, split–split plot design: clipping of understory vegetation (cut, uncut), and leaf litter manipulations (removal, addition, control). As expected, experimental gaps dramatically increased tree seedling recruitment, but gap effects varied among litter treatments. Litter addition reduced recruitment in gaps, but enhanced recruitment under intact canopy. Species composition of recruits also differed markedly between gap treatments: several small-seeded pioneer and long-lived pioneer species recruited almost exclusively in gaps. In contrast, a few medium-to-large-seeded shade-tolerant species recruited predominantly under intact canopy. Leaf litter represents a major barrier for seedling emergence and establishment of small-seeded, shade-intolerant species, but enhances emergence and establishment of large-seeded, shade-tolerant species, possibly through increased humidity and reduced detection by predators. Periodic clipping of the understory vegetation marginally reduced tree seedling mortality, but only in experimental gaps, where understory vegetation cover was greatly enhanced compared to intact canopy conditions. Successful regeneration of commercially valuable long-lived pioneer trees that dominate the forest canopy may require clear-cutting, as well as weeding and site preparation (litter removal) treatments in felling clearings. Management systems that mimic natural canopy gaps (reduced-impact selective logging) could favor the regeneration of shade-tolerant tree species, potentially accelerating convergence to old-growth forest composition. In contrast, systems that produce large canopy openings (clear-cutting) may re-initiate succession, potentially leading to less diverse but perhaps more easily managed “natural plantations” of long-lived pioneer tree species.     

Changes in soil chemical and physical characteristics in Japanese cypress (Chamaecyparis obtusa Endl.) stands by mixture of deciduous broad-leaved trees in the northern Kanto region of Japan

In order to clarify the effects of a mixture of deciduous broad-leaved trees on soil fertility, we investigated litter biomass accumulation, mineral soil chemical and physical characteristics, characteristics of nitrogen mineralization, and the mutual relationships between them in Japanese cypress (Chamaecyparis obtusa) stands mixed with deciduous broad-leaved trees at different ratios (mixture ratio; MR = 0, 16, 33, 43, 100% by basal area) in the northern Kanto region of Japan. Litter biomass in the forest floor and mineral soil was 19.1 Mg ha⁻¹ in MR 0% and decreased approximately 60 % in MR 33%, MR 43% and MR100%. The permeability at 0–5 cm soil depth in MR100% was twice as much as that in MR 0%. Increases in soil permeability were likely due to larger soil pores in the higher MR with much accumulated deciduous broad-leaves. At 0–5 cm soil depth, the differences in carbon concentration among the plots were not clear. On the other hand, carbon concentrations at 5–10 cm depth increased from 90 g kg⁻¹ to 147 g kg⁻¹ with increases in MR from 0% to 100%. Concentrations of exchangeable bases increased two to four times with increases in MR from 0 to 100% at 0–10 cm depth. Soil pH (H₂O) generally increased with increases in MR at each depth. The rates of net nitrogen mineralization at 0–5 cm depthin vitro increased from 25 to 87 mg kg⁻¹ 2 weeks⁻¹ with increases in MR from 0 to 100%. However, increases in nitrification with increases in MR were not clear compared with nitrogen mineralization. These results indicated that a mixture of deciduous broad-leaved trees in a Japanese cypress stand was effective in preventing soil fertility decline. This study was supported by a grant from the Showa Shell Sekiyu Fundation for Promotion of Environmental Research. A part of this study was presented at the 7th International Congress of Ecology (1998).     

Influence of three plant species with different morphologies on water runoff and soil loss in a dry-warm river valley, SW China

Understanding of the effects of isolated plants with different morphologies on water runoff and soil loss is important for vegetation restoration in arid environments. We selected three representative species (Artemisia gmelinii; Ajania potaninii; Pulicaria chrysantha) of the dry-warm river valley of the upper reach of Minjiang River, SW China to examine these effects. Twenty-five runoff events were recorded using runoff plots at micro scale (<40 cm × 40 cm) on a south facing slope from July through October 2006. A. potaninii had sparse canopy, the smallest leaf area (0.49 ± 0.25 cm²) and specific leaf area (67.8 ± 16.5 cm²/g), and the highest leaf relative water content (27.1 ± 4.4%). It is the most resistant to drought stress. A. gmelinii was the shortest, and had relatively small leaf area (0.55 ± 0.50 cm²) and the densest canopy. P. chrysantha had the greatest leaf area (1.41 ± 0.49 cm²) and most extended canopy (4450 ± 1646 cm²). Dead branches and leaves of A. gmelinii and P. chrysantha commonly fall and collect on the soil surface. Thus they had greater improvements on soil porosity and soil water content, and higher effectiveness in controlling soil loss. However, A. gmelinii had more stable effectiveness in controlling runoff as compared with P. chrysantha. The characteristics such as relatively small leaf area but low height and dense canopy might be one criterion for selecting species to improve soil properties and controlling runoff and soil loss. Differences in soil environments, and runoff and soil loss production capacity for micro-surfaces regulates water and materials redistribution, which emphasizes the importance in designing vegetation restoration pattern.     

Performance of eight tree species in the highland Vertisols of central Ethiopia: growth, foliage nutrient concentration and effect on soil chemical properties

The coverage of trees in the highland Vertisol areas of Ethiopia is very scarce. A tree screening trial was conducted from 1997 to 2002 in Ginchi (central Ethiopia) to select fast growing and high biomass producing tree species; evaluate foliage macronutrient concentration of different tree species; and assess effects of trees on soil chemical properties beneath their canopies. Acacia decurrens Willd, A. mearnsii De Wild and Eucalyptus globulus Labill attained the highest height growth at 64 months as compared to other indigenous and exotic species. E. globulus provided better height increment from 24 to 36 and 36 to 64 months than other tree and shrub species. Acacia mearnssi and A. saligna Labill Wendl produced high biomass at 40 and 64 months. Differences between the highest and lowest dry biomass at 12, 40 and 64 months were 1.13, 29.19 and 38.89 kg tree⁻¹, respectively. None of the tree species resulted in a foliage to stem biomass ratio of >0.98 at 40 and 64 months. Sesbania sesban (L.) Merr had high N and P concentrations in its foliages and stems at 12 and 40 months. Total N under Acacia abyssinica Hochst. Ex Benth, A.␣saligna and S. sesban was slightly greater at 40 months than 12 months.